Fuse for antiaircraft projectiles



Aug. 9, 1932. T. B. DOE

FUSE FOR ANTIAIRCRAFT PROJEGTILES Filed Aug. 14, 1931 6 l @all/554 l Patented Aug. 9, 1932 PATENT oFFicE N THOMAS IB. DOE, GF NEW YORK, N. Y.

FUSE FOR ANTIAIRCRAFT PROJECTILES Application led August 14, 1931. Serial No. 557,048.

This invention `relatesto fuses for projectiles, particularly to the type of projectile which isdetonated at a predetermined point flight.` These projectiles are largely employed yin anti-aircraft gun fire. More particularly my invention constitutes an im- `provement in the type of fuse disclosed in my prior Patent N o. 1,863,838 issued June 21,

`1,932 for fuse vfor anti-aircraft projectiles. In

this type` of fuse the projectile is detonated when the air pressure on the nose thereof falls `below alpredetermined amount, the air pressure at each instant being a function of the `speed of the projectile and, therefore, a function of thedistance of the same from the -liring point.` The air pressure on the nose is,

therefore,`balanced against a settable yielding means within the projectile, such as a fspring. According to the present invention a plurality of sprlngs of graduated strength are employed in order to increase the accuracy of the setting.

A further object of the invention is to im- D prove upon the safety locking device which prevents the possibility of premature explosion. l

`Referring tothe drawing showing several `possible embodiments of my invention:

: Fig. 1 is a vertical section through the firing mechanism of the shell constructed ac- Acording to my; invention.

Fig. 2 is a similar section showing the preferred formof; spring setting means.

Fig. 3 is a transverse section taken on line `3 3 of Fig. 2.

'Fig.`4 is a detail sectional view of the cage or. `sai'ety. `member `for preventing premature A escape ofthe locking ball.

Fig. '-5 is a vertical sectional view taken at right `angles to` Fig. 2 but with a number of parts shown in elevation;

According to `my invention the firing pin i or hammer 1 is placed .in a transverse channel 2extending across the nose of the fuse cap, thehammer being normally locked in its mid position in said channel 2. The channel is shown extending entirely through the main body of the fuse, the outer ends being threaded to receive detonator caps 3 and 4 which may be screwed into place after the fuse and shell are otherwise completely assembled. Said caps communicate with the usual powder train channels 5 leading downwardly into the main body of the shell (not shown). Centrifugal force, due to rotation of the shell,` is relied upon to actuate the hammer as soon as it is released from the locking detent 6. The detent is shown as having mounted on its upper end a eupshaped member 7 exposed to the air pressure created by the rapid passage of the shell through the air. `For this purpose there is shown a small bore 8 leading from the nose lof the projectile to` a chamber or generally U-shaped bore 9 so that the air in this cham- .ber is compressed when the shell is in Hight ber 12 is prevented from rotating by having the ends and teeth thereon pass between the two parts of the split hub 16' which is rnfily screwed into place on internal threads 17 in the body 30 of the fuse cap, thus holding base j part 31 to body 30 with ring 13 between.` The ring 13 may be set with reference to a finely graduated scale 18 on the bottom of the fuse cap.

For preventing premature withdrawal of the detent and possible premature explosion, I have shown a lockingball 19 placed within the cup so that the top of the ball just clears the top or roof of the chamber 9. Therefore, as long as the ball lies in the cup 7 the detent cannot be withdrawn. It should be noted that the lowest part of the cup is in the center. This shape tends to prevent the escape of the ball, not only when the shell is at rest on its base, but also as long as the shell is receiving its terrific acceleration in the muzzle of the gun. AAfter such acceleration ceases, however, the centrifugal force quickly throws the ball out of the cup. To prevent accidental,displacement of the ball from the cup I have shown a ring-like cage 2O surrounding the cup. This cage has afplurality of fiexible fingers 2l extending upwardly above the rim of the cup so that the ball cannot escape. The fingers, however, are madev flexible enough so as not to interfere with the escape ofthe ball after-r the shell is rotating during flight. Member 20, therefore7 is preferably made of some soft metal, such as copper, so that when the ball strikes a finger with appreciable force the finger isbent over and the'ball escapes, the ball being then held in" its outermost position by centrifugal force. VMember is clamped within the shellby spring ring 20 forced within the same to hold it within a counter-sunk top 29 of the main body of the fuse cap.

In thepref'erred form of the invention shown in Figs. 2 to 5,5a plurality of springs of graduated strength are employed instead of the one spring'lO. As shown there is placed at the bottom4 a short stiff spring 22.

This spring rests at its bottom against theV adjustable member l2 hereinbefore described and.' at its top against a Vwasher 23, slidably vmounted in a sleeve 24 within an annular member 25 held in place within the split nut 16. Above said washer is placed a second spring 26 of lesser stiffnessrrwhichbears atits top against a second washer 27, also slidably mounted withinfthe sleeve 24. Abovel the `latter washer is shown still a third and'weaker Vspring 28, shown as bearing at its top against the collar ll on the detent 6'. The purpose of these graduatedY springs willbe read-ilyV appreciated when it is remembered Ythat the velocityV of the shell in fiight'from point to point` does not decrease Yuniformly in a straight line function but falls off much more rapidly during the'high velocity first portion of its flight than during the slower velocity latter portion of its iiight. Therefore,in order to obtain a sensitive means responsive to small ,pressurev changes` during the latter portionof the flight, itis desirable to provide a separate stronger andless sensitive means which shall be effective' during Y the first portion of the yiight. With the graduated springarrangem'ent described it will readily be seen thatfduring the first portion of the flightonlytheheavy spring. 22 will be operative, the others, being compressed so that the collar 28 on the detent i gether with the apparatus which I now consider to represent lthe best embodiment thereof, but Idesire to have it understood that the apparatus vshowng-'is only illustrative and that the invention can be carried out by other means. Also., whilevit is designed to use the various features and elements in the combination and relations desc'ribe'd,gsomeof these may beV altered and others. omitteduwithout interferingV with the morez'g'eneral results outlined,'and the invention extendstofsueh Having described invention, `whatfl claim and desire tosecure Lettersl Patent is.: l. AIn a fuse for projectiles, theV eombinaf tion with the firing pin and locking detent,

Vof means for withdrawing said detent Ya-t-a predetermined point-in the flight of' the shell anda safety lo'clr'for preventing rpremature release vin the gunbarrel comprising acup on said detent, a ball'in said cup which prevents lifting ofthe Vdetent while insaid cup, anda flexible cage for preventing untimely 'escape of the ball from said cup.`

2. lnV a fuse forI projectiles, the combi-nation with the. firing pin and locking detent,'of means for withdrawing said detent'a't a predetermined point in the flight of the. shell and a safety lock for preventing premature release-inthegun barrel comprising acup -on said detenga ball in said cup which pre- "vents lifting ofthel detent while-.in said cup,

and flexible fingers for preventing untimely escape of the-ball fromthe` cuplwhile not interfering'with'the-balls escape under the Aaction of 4'the c entrifugal'force due/tothe shells rotation in flight. i A

3. Tn a fuse for profectiles,thefcoinbina.- tionfwith the hammer, of ai detent'for normally hollingsaid hammer retracted, means subject to the air pressurel due to thefliglrt of the projectile for vholding said detent in place, and spring means opposing said other Ymeans for withdrawing the detent comprising a plurality of springslof graduated' relative stiffness forV the. purpose specifiedf YTnV a fuse'for'prejectiles; elba'carabina-VVV tion with the hammer,:ofa detentfor; normally holding said hammer -retracted.=,.m'eans subject to theV ai'r 'pressure' due' tothe flight fim ias

ofthe projectile for-holding'said vdetent in.M

place,and spring means opposing said other means for withdrawing the detent comprising a plurality of springs 'of graduated relative stiffness which come into operation successively as the air Vpressure diminishes.

5. In a fuse for projectiles, the combination with the hammer, of a detent for normally holding said hammer retracted, means subject to the air pressure due to the flight of the projectile for holding said detent in place, spring means opposing said `other means for withdrawing the detent comprising a plurality of springs of graduated relative stiffness, and means for setting said springs for range whereby for the longer ranges the less still and more sensitive springs are eective and for shorter ranges the stiffer and less sensitive.

In testimony whereof I have aiiXed my signature.

THOMAS B. DOE. 

